Ventilation Systems - doe-std-1128-98

DOE-STD-1128-98

Carpets are not recommended because they are difficult to clean and survey and

bulky to dispose of and they do not adequately protect the underlying surface. In

some areas, such as control rooms, their use may be justified by noise control

requirements; however, their contamination control limitations should be

considered. If used, carpets should be surveyed frequently and disposed of as

radioactive waste when they become contaminated.

10.2.2

Ventilation Systems

In addition to decommissioning considerations, the design of the ventilation system

will depend on the operations that will be conducted in the facility. Adequate air

flow for all operations and good design practices will help keep the facility clean

during operations and will facilitate decommissioning. Fiberglass duct work may

present a fire hazard and may be more difficult to decontaminate than stainless

steel, especially stainless steel that has been electropolished. Welded joints are less

likely to collect contamination than bolted ones; however, bolted joints are easier to

remove and the most contaminated areas are readily accessible for cleaning.

Filters should be positioned in ventilation systems to minimize contamination of

ductwork (e.g., filtration of glove-box exhaust air before it enters a duct leading to

a plenum).

10.2.3 Piping Systems

Potentially contaminated piping systems that are imbedded in concrete are a

common and relatively expensive decommissioning problem. Most often, they

must be sealed and removed last, after all other radioactive material has been

removed and the building is being demolished by conventional methods. Often,

they provide the major impetus for demolishing a building rather than converting it

to some non-nuclear use. For this reason, it is best to run pipes in chases or tunnels

that have been lined (usually with stainless steel) to prevent contamination from

penetrating building surfaces. To minimize hand jackhammer work required during

decommissioning, floor drains should not be enclosed in concrete.

10.2.4 Soil-Contamination Considerations

Depending on the activity levels found, locations where contaminated effluents

have penetrated the ground may require excavation during decommissioning. The

facility design should minimize such areas. Particular attention should be paid to

storm runoff from roofs, storage areas, contaminated equipment storage, and liquid

waste treatment impoundments (including sanitary sewage systems if they may

receive some small amount of contamination during the life of the facility.)

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